Pot broaching machine

ABSTRACT

A machine for broaching external gears comprising a frame, a pot broaching tool positioned with its axis vertical at the upper portion of the frame, a piston and cylinder device with its axis vertical located directly beneath the pot broach. The gear blank is positioned directly above a work support carried by the piston and is pushed upwardly through the pot broach to a position of clearance above. The cutting teeth of the broach are of course directed downwardly and each cutting tooth has a chip receiving space directly beneath it into which chips are formed during the broaching operation and from which chips are displaced for downward discharge.

United States Patent Psenka [45] Apr. 18, 197 2 [s4] POT BROACHINGMACHINE Primary Examiner-Gil Weidenfeld [72] Inventor: Joseph A. Psenka,Bloomfield Hills, Mich. 4"orney whmemre Hume & Belknap [73] Assignee:Lear Siegler, Inc., Santa Monica, Calif. [57] ABSTRACT [22] Filed: Mar.5, 1970 A machine for broaching external gears comprising a frame, a potbroaching tool positioned with its axis vertical at the upper [2]] Appl'l6747 portion of the frame, a piston and cylinder device with its axis52 us. c|..; ..90/I0, 90/1, 90/86 vertical located directly beneath theP breach The gear [51] Int. Cl. ..B23f5/28 lank i po i ioned irectlyabove a work support carried by 58] Field of Search ..90/ 10,, 86, l hepiston an is pushed upwardly through the pot broach to a 56 R i cudposition of clearance above. The cutting teeth of the breach 1 e erencesI are of course directed downwardly and each cutting tooth has UNITEDSTATES PATENTS a chip receiving space directly beneath it into whichchips are formed during the broaching operation and from which chips3,541,921 1 l/ 1970 l-lelfer et al. ..9 0/ 1 are displaced for downwarddischmga 1,909,840 5/1933 Muller ..90/l0 Y FOREIGN PATENTS ORAPPLICATIONS v 424,956 6/ 1933 Great Britain ..l "90/10 4Claims,3DrawingFigures l'l ll n I: u

POT BROACIIING MACHINE BRIEF SUMMARY OF THE INVENTION Machines forbroaching all of the teeth on an external gear as a consequence of asingle passage of a work blank through a generally tubular broach areknown. The teeth of the broach are arranged in longitudinal alignmentand are appropriately stepped to perform the required cutting operation.If the gear is to be broached is a spur gear the teeth are arranged inseries extending parallel to the axis of the broach. If the gear is ahelical gear the teeth are arranged in helically extending se- I'ICS.

In accordance with the present invention the generally tubular potbroach is rigidly supported in an elevated position with its axisvertical. Located directly beneath the broach is a piston and cylinderdevice in which the piston is displaced upwardly during a cuttingstroke. A piston rod connected to the piston is connected to a worksupport above the piston which is adapted to receive and carry a gearblank upwardly through the broach.

A single passage of the gear blank upwardly through the broach resultsin a complete cutting operation forming the teeth as required on theperiphery of the broach. The gear is moved upwardly above the upper openend of the broach into a clearance position relative-to the broach. Itis at this time moved from the work support to a downwardly directedchute.

Preferably, automatic means are provided for loading the machine andcomprises means for advancing work blanks into a preliminary positiondirectly above the work support. Upward movement of the piston causesthe work support to pick up the gear blank and to transport it throughthe generally tubular broach.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front elevation of thebroaching machine.

FIG. 2 is a side elevation of the machine shown in FIG. 1.

FIG. 3 is a fragmentary sectional view through the broaching tool.

DETAILED DESCRIPTION Referring now to the drawings, the machinecomprises a frame indicated generally at which as illustrated comprisesside plates 12 connecting to a front plate 14 and a bottom plate 16.Fixedly secured to this frame at the front thereof and adjacent its topis a pot broach 18 which comprises an outer shell or housing receiving amultiplicity of toothed cutting elements. Details of the broach itselfform no part of the present invention but it may for example be of thetype disclosed in my prior US. Pat No. 3,332,129.

Also fixedly carried by the frame 10 is a piston and cylinder device 20in which a piston (not shown) is vertically movable. At the upper end ofthe piston and cylinder device 20 there is provided a work support 22which is cdnnected to the upper end of a piston rod 24.

Automatic loading mechanism is preferably provided and comprises asupport 26 extending laterally from the frame and having work feedingmechanism indicated generally at 28 movable across the front of themachineby a feed piston and cylinder device 30 to position a work pieceW directly above the work support 22.

Referring now to FIG. 3 there is a fragmentary sectional view showingthe disposition of the cutting teeth in the broach. In this Figure thecutting teeth 32 on the broach are formed on the inner circumference ofrings 34. Each of the rings is so shaped that a chip receiving recess ispositioned directly below each cutting tooth which receives the chipsduring the broaching operation. As soon as a work piece has been movedupwardly past a particular ring, the chips which have been formedthereby in the space 36 may be dislodged by suitable means such forexample as oil, and permitted to fall downwardly through the broach, bygravity.

At the top of the frame 10 there is positioned a discharge chute 40 intowhich cut gears are transferred by suitable means from the work support22 for downward delivery by gravity.

The foregoing arrangement provides the most efficient relationshipbetween the broach and the work advancing means and permits the machineto occupy a minimum vertical dimension. If desired, the lower end of thepiston and cylinder device 20 may extend below the floor level.

In a particular machine the piston and cylinder unit has been selectedto have a 45-inch stroke so that the location of the loading equipment26 and the initial position of the work blank W, before it is advancedthrough the broach, is at a convenient height for inspection andhandling.

One of the particular advantages of the defined arrangement is that thework support is particularly well adapted to support the work pieceduring initial movement of the work piece into the broach. This isaccomplished by providing conventional guide means for the piston rod atthe upper end of the cylinder which due to its separation from thepiston during the initial upstroke of the machine will support and guidethe work piece during this initial movement. After the blank has moved asubstantial distance into the broach so that the engagement between thebroach and the partially broached work piece is increased, the movementand location of the work piece is accomplished substantially completelyby the broaching tool.

While reference has been made to a pot broach assembly using rings, thepresent invention is of course equally applicable to a stick type potbroach in which thebroach assembly consists of a series of individualelongated rectangular broach inserts; or arcuate slab type in which theassembly consists of a multiplicity of elongated sector broach elements;or peg type in which individual teeth are provided. The importantconsideration is that the cutting teeth are positioned in downwardlyfacing cutting position.

The present arrangement affords the best solution as regards rapidloading of the parts and the inverted dish principal provides the mostideal chip disposal system. This arrangement also simplifies theunloading or ejection problem which is accomplished simply by removingthe finished gear from the work support at the position which itoccupies at the end of the cutting stroke above the upper open end ofthe broaching tool.

I claim:

1. A pot broaching machine comprising a frame, I

an elongated generally tubular pot broach having open upper and lowerends and being fixedly mounted adjacent the top of the frame with itsaxis vertical,

an elongated power cylinder fixedly mounted on the frame directlybeneath said broach with its axis vertical and parallel to the broachaxis and having its upper end closely adjacent to the lower end of saidbroach,

a piston in said cylinder having a piston rod connected thereto andextending above said cylinder,

a work support at the upper end of said piston rod, an automatic loadingmechanism located above the work support in the lower position thereof,said mechanism including;

means intermediate the upper end of said cylinder and the lower end ofsaid broach for supporting a work piece above the work support on saidpiston rod for engagement thereby upon initial upward movement of saidpiston,

said piston being movable in said cylinder in a stroke to cause saidwork support to move'from a clearance position below the lower end ofsaid broach to 'a position above the upper end of said broach,

said broach comprising a housing having therein a multiplicity oflongitudinally extending series of stepped downwardly directed cuttingteeth,

the teeth being shaped to provide a chip receiving space directlybeneath each cutting tooth from which chips may be dislodged fordownward discharge after the work pieces have moved upwardlytherebeyond. 2. A machine as defined in claim 1 in which said mechanismcomprises a slide movable horizontally to move said work piece with itsaxis vertically disposed into position directly above the work support.

3. A machine as defined in claim 1 which comprises unloading mechanismlocated above the upper open end of said

1. A pot broaching machine comprising a frame, an elongated generallytubular pot broach having open upper and lower ends and being fixedlymounted adjacent the top of the frame with its axis vertical, anelongated power cylinder fixedly mounted on the frame directly beneathsaid broach with its axis vertical and parallel to the broach axis andhaving its upper end closely adjacent to the lower end of said broach, apiston in said cylinder having a piston rod connected thereto andextending above said cylinder, a work support at the upper end of saidpiston rod, an automatic loading mechanism located above the worksupport in the lower position thereof, said mechanism including; meansIntermediate the upper end of said cylinder and the lower end of saidbroach for supporting a work piece above the work support on said pistonrod for engagement thereby upon initial upward movement of said piston,said piston being movable in said cylinder in a stroke to cause saidwork support to move from a clearance position below the lower end ofsaid broach to a position above the upper end of said broach, saidbroach comprising a housing having therein a multiplicity oflongitudinally extending series of stepped downwardly directed cuttingteeth, the teeth being shaped to provide a chip receiving space directlybeneath each cutting tooth from which chips may be dislodged fordownward discharge after the work pieces have moved upwardlytherebeyond.
 2. A machine as defined in claim 1 in which said mechanismcomprises a slide movable horizontally to move said work piece with itsaxis vertically disposed into position directly above the work support.3. A machine as defined in claim 1 which comprises unloading mechanismlocated above the upper open end of said broach operable to receive afinished work piece and to retain it upon return downward movement ofthe work support.
 4. A machine as defined in claim 1 in which the broachteeth are provided in a multiplicity of rings, each ring having at itsinner surface a series of annularly arranged teeth, the teeth inadjacent rings being in longitudinal alignment.